Conventionally, an electric beauty device such as an electric razor, an electric hair clipper, an electric toothbrush or an electric face-wash brush, incorporates a motion conversion apparatus that converts rotational motion of a motor incorporated therein into reciprocating motion. An inner blade of an electric razor, a movable blade of an electric hair clipper, a toothbrush of an electric toothbrush or the like is coupled to the motion conversion apparatus and brought into reciprocating motion, whereby desired beautification treatment is performed. Such motion conversion apparatus suffers from a low efficiency of conversion from rotational motion to reciprocating motion.
In recent year, from the perspective of motion conversion efficiency, beauty devices using an electromagnetically driven linear actuator have been known (for example, Patent Literatures 1 and 2). A general linear actuator includes a fixed element including a coil and a movable element that is a magnetic body, and performs desired beauty treatment by driving the movable element to reciprocate relative to the fixed element via an electromagnetic force.
In particular, Patent Literature 2 discloses a linear resonant actuator to be used for an electric razor, the actuator including a reciprocating motion-type electric motor drive for bringing a movable element into reciprocating motion relative to a fixed element. This electric motor drive is compatible with a movable blade of any of various blade heads and includes a plurality of movable elements to be driven by a single fixed element, the movable elements having natural frequencies that are substantially equal to one another. Also, what is called resonant rotation-type actuators employing a VCM structure have been known (see, for example, Patent Literature 3).